Diffractive trijet production in high energy DIS.
We work in a frame where both the virtual photon and the hadronic target carry zero initial transverse
momentum, the photon carries large \(p^+\)  component of light cone momentum, while the hadronic target – large \(p^-\)  component.
The virtual photon fluctuates into a dipole (quark-antiquark pair), which then eikonally interacts
with the hadron.
The virtual photon-nucleon/nucleus cross section can be expressed as dipole-nucleon/nucleus cross section weighted over the dipole wavefunction.
To lowest perturbative order this scattering is given by a two-gluon process, see Fig. REF . One gluon is absorbed by the dipole while
the other gluon interacts with the dipole and then emerges in the final state.
We focus on a final state observable containing a (color singlet) \(q\bar{q}\)  dijet and the third jet originating from the nucleus.
Note that we are interested in different kinematics compared to commonly considered in the literature [1]}, [2]}, [3]}, [4]}, where all three jets are measured on the photon side.
Our calculation is performed in the framework of the Color Glass Condensate (CGC) effective theory [5]}, [6]}, [7]}.
